The Application of Genetic Bit Analysis to Forensic Loci
William J. Watson , B.S. and Robert C. Benjamin, Ph.D.
University of North Texas, Department of Biology, Denton, TX
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Genetic Bit Analysis (GBAtm ) is a PCR-based method for typing single nucleotide polymorphisms (SNPs). GBA can be separated into two major procedural components: sample processing and product detection. Sample processing begins with a genomic DNA isolation step suitable for use with PCR. A target SNP locus is amplified using one normal and one modified primer. The unmodified strand of the PCR product is eliminated using 5'-3' exonuclease. Product detection is accomplished by hybridizing the remaining single-stranded product to a complimentary immobilized probe. The probe binds to the sequence immediately 3' to the SNP, and is extended by one of several different haptenated ddNTPs. Enzyme-linked colorimetry is then used to determine which labeled ddNTP is incorporated.
Although any SNP locus has the potential to be assayed using GBA, the purpose of our study was to evaluate the application of the GBA process to genetic loci currently used in the analysis of forensic and database samples. Human DNA samples previously typed using conventional PCR typing techniques were retyped at the same loci using GBA. A comparison of typing results between the two systems was made, with an emphasis on accuracy and reproducibility. The results of this comparison will be discussed.
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